Studies will be conducted to explore the mechanism involved in the metabolism of free and esterified sterol by tissue culture cells. The type of sterol synthesized by cells will be established and the interrelationship between sterol content and content of other cellular lipids will be determined. The relationship between sterol flux and synthesis will be studied. The regulation of individual metabolic steps in sterol synthesis will be examined. BIBLIOGRAPHIC REFERENCES: Arbogast, L.Y., G.H. Rothblat, M.H. Leslie and R.A. Copper. Cellular cholesterol ester accumulation induced by free cholesterol-rich lipid dispersions. Proc. Nat. Acad. Sci. U.S.A. 73: 3680, 1976. Rosen, J.M. and G.H. Rothblat. Origin of fatty acids of cholesteryl ester. Lipids 12: 222-227, 1977.